How can I know if traffic is fake or not?

[TordB.com]

I've found some sites that pretty good traffic every month. And I've seen stats from a couple of months, however, how can I know if it's fake or not? Just wondering.

 

[weblord]

http://www.namepros.com/parking-and-traffic-monetization/535755-whats-best-way-tell-if-traffic.html